Feeding movement for sizer shoe of concentric grinder



y 1962 G. M. SNYDER 3,031,805

FEEDING MOVEMENT FOR SIZER SHOE OF CONCENTRIC GRINDER Filed April 1, 1959 4 Sheets-Sheet 1 FIG.

INVENTOR GLENN M. SNYDER ATTORNEYS G. M. SNYDER May 1, 1962 FEEDING MOVEMENT FOR SIZER SHOE OF CONCENTRIC GRINDER 4 Sheets-Sheet 2 Filed April 1, 1959 FIG. 2. GLENN m. SNYDER INVENTOR WM M,mm+

ATTORNEYS May 1, 1962 G. M. SNYDER 3,031,805

FEEDING MOVEMENT FOR SIZER SHOE OF CONCENTRIC GRINDER Filed April 1, 1959 4 Sheets-Sheet 3 FIG. 3.

1N VENTOR ATTORNEYS y 1, 1962 l G. M. SNYDER 3,031,805

FEEDING MOVEMENT FOR SIZER SHOE OF CONCENTRIC GRINDER Filed April 1, 1959 4 Sheets-Sheet 4 REVERSE FIG. 4.

GLENN. M SNYDER INVENTOR ATTORNEYS g a is w .9 a re The specification which follows relates to a feeding movement for the sizer shoe of a concentric grinder and the like of the type shown in Patent No. 2,799,977, granted July 23, 1951 on the invention of H. E. Balsiger and A. J. Jones.

In the precision grinding of small, round articles-such as the races of ball bearings and similar devices, during the final part of the grinding cycle, the workpieces must be fed aginst the rotating grinding wheel by a shoe or the like. This shoe serves the purpose also of establishing the final size of the finished work.

It is the object of this invention to provide a novel sizer shoe which will support the workpiece at a point substantially diametrically opposite the contact point with the grinding wheel.

It is also an object of the invention to support this sizing shoe in a manner which will insure that it is retracted at the conclusion of the grinding operation.

Among the objects of the invention is to provide linear motion to the sizer shoe at varying rates of speed culminating in the final position when the workpiece has been completely finished.

A further object of the invention is to provide precise control for the position of the sizer shoe by predetermined settings of the several parts of the mechanism.

The precise control can be carried out including retraction of the shoe for loading workpieces without, however, impairing the precision of control.

The control of the sizer shoe is accomplished by a cam which allows a rapid approach of the shoe to the work followed by a relatively slower advance during grinding. Furthermore, the motive power utilized for advancing the sizer shoe permits variable rates of feed at the option of the operator.

Another object, therefore, is to provide a cam of predetermined contour to provide a controlled movement of the shoe during the feeding of the workpiece against the grinding wheel.

A further object is to provide a positive stop for coacting with a stop surface on the periphery of said cam whereby to provide a more sensitive mean for controlling the size of the workpiece.

The retraction of the sizer shoe is rapidly accomplished mechanically without affecting the setting of the adjustments for the advance and stoppage of the sizer shoe.

As exemplifying the invention I have illustrated the preferred form on the accompanying drawings in which FIG. 1 is a side elevation of sizer shoe and its operating movement;

FIG. 2 is a plan view;

FIG. 3 is a front elevation of the same and FIG. 4 is a diagram of the electric and fluid pressure A at 3.

circuits used in feeding the grinding wheel and sizer shoe.

Fatenterl May 1, 1362 The base supports a plate 7. This plate 7 is the foundation upon which front spring 8 and rear spring 9 are bolted or otherwise attached. These springs are so adjusted that they are biased toward the rear.

Springs 8 and 9 support a carriage 19 which is bolted on the springs in fixed position. This carriage is normally in its rear position due to the bias of springs 8 and 9.

A front sizer shoe 11 forms part of the carriage it This shoe has a wear plate or button 12 for engagement with the workpiece.

The workpiece 13 is illustrated as the inner bearing race of a ball bearing.

The workpiece 13 is mounted in customary manner on magnetic chuck 14 which in turn is held by the headstock 15 of the rotary grinding machine.

The carriage 10 has a lateral ofiset extension 16 at the rear. The lateral extension is drilled horizontally from front to rear and screw-threaded to receive an adjustment screw 17. The rear end of the adjustment screw carries a wear button 18 of hardened metal. The adjustment screw 17 is fastened in adjustment by means of the lock nut 19.

A bracket 20 mounted on the base 6 carries a journal 21 which extends into the plane of the carriage 16 Journal 21 supports a ring cam 22 mounted on preloaded ball bearings so that it will be rigidly supported in any adjusted position.

The hydraulic cylinder 23 is pivotally mounted upon a yoke 24 on the front of the base 6.

The ring cam 22 supports a stud 25. This stud is connected by a rod end to the piston rod 26.

When the piston rod 26 is in its forward or retracted position, the ring cam is oscillated counterclockwise to bring a short diameter sector 27 opposite the button 18. Adjacent the short diameter there is a. gentle slope or rise 28 terminating in a large diameter land 2 9. This land has the maximum diameter but is not concentric with the journal 21. The land has a progressively increasing diameter with a total lift equal to the amount of feed required.

The sector 27 when opposite the button 13 permits full retraction of the sizer shoe 12. This provides ample space for loading and unloading the workpieces 13 on the magnetic chuck.

As the piston rod 26 is extended at a controlled speed, the slope 28 of the cam advances the carriage 19 and the sizer shoe 12 rapidly to the point Where shoe 11 engages the work 13 slightly above the horizontal plane through the point of contact of the work with the grinding wheel.

At the conclusion of fast grinding, the outer land 29 bears against the button 18 and provides a gradual advance depending upon the feed of pressure fluid to the cylinder 23.

The limit of clockwise movement in the advance of the ring cam 22 and the sizer shoe 12, is controlled by an outstanding shoulder 30 on the ring cam 22. This shoulder 30 has a hardened face 31.

The bracket 20 carries a lateral extension 32. An adjustment screw 33 is threaded vertically through the extension 32. The screw 33 is held in fixed adjustment by means of a lock nut 34. The lower end of the screw 33 carries an abutment 35 which is in the path of the hardened face 31 on the shoulder 30. Adjustment of the screw 33 determinesthe extent of travel of the button 18 over the top of the cam 29 and the finished diameter of the work 13.

Introduction of pressure fluid into the left end of the cylinder 23 retracts the piston 26 to its extreme right hand position, releasing the button 18 successively from the cam surfaces 29 and 28. The retractile springs 8 and 9 then move the sizer shoe 12 away from the workpiece. The workpiece may then be removed and replaced with another one after which the cycle of movement is repeated.

The workpiece is illustrated as an inner ball-bearing member 13, the groove of which is to be accurately ground to size determined by the form of the cam 22, and the setting of the screws 17 and 33. The workpiece is supported on an arbor 37 having upper and lower work supporting shoes 38 and 39. These support the work during its rotation. The screws 17 and 3&3 serve to hold the workpiece 13 and cam 22 in adjjusted positions opposite the grinding wheel 4d. The latter is advanced and retracted once in each cycle of operation.

The operation of the cam 22 and its relation to the grinding operation and cycle in general is shown on the diagram FIG. 4.

Electric current is supplied from a line Ll, L2.

A pump 41' maintains the necessary hydraulic pressure. Fluid under pressure is supplied through main 42 to a cylinder 43 having a reversing valve 44. The valve is movable manually by the starting lever 45 which moves to the right to start the grinding operation. At this time the solenoid 46 connected to the valve 44 is inactive.

The opposite ends of cylinder 43 discharge freely to a return duct 47.

Fluid under pressure leaves cylinder 43 by way of duct 43 to one end of the feed cylinder 49 for the grinding wheel slide d. The piston 51 in the cylinder 4% is attached to" the slide 50 by the piston rod 52 in the usual manner. The advance of the wheel slide 56 continues until it reaches a jet stop 53.

The jet stop 53 is fed with fluid under pressure from main 42 through duct 54, a restriction 55 and duct 5%. When the slide 50 reaches its limit of travel it blocks the free discharge from stop 53 and builds up pressure in duct 56.

A relief valve (VR) 57 returns excess pressure fluid to a common reservoir.

Fluid under pressure is at all times delivered to the midpoint of the cam reversing cylinder 53 through duct 59 leading from main 42. This reversing cylinder has a piston 64) which is biased to the left by means of spring 61. In this position the valve discharges fluid under pressure through duct 62 to the right end of the cylinder 23. This causes the cam 22 to rotate clockwise and advance the carriage 10.

Increase in pressure in duct 56 due to the proximity of the slide 50 to the stop 53 builds up pressure as far as relief restriction 63 and pressure switch 64. Switch 64 has a normally open contact 65 connected through a timing relay (TR) 66 to the line L1. After a predetermined time relay 66 closes a switch 67 connecting solenoid 46 to L1. This shifts valve 44 to the left reversing the feed of pressure fluid from cylinder &3 through duct 68 to the left of feed cylinder 49. The slide 59 is therefore retracted for the next cycle of operation.

Operation At the start of operation normally closed switch 69 completes the circuit from L1 through solenoid 70 to L2. Solenoid 70 is connected to piston 69 and holds the latter to the right against spring 61. Fluid under pressure thus reaches the left end of cylinder 23 through duct 71 and holds the piston rod 26 in retracted position and the cam 22 inoperative.

When pressure switch 64 is operated, the contact 69 is opened, solenoid 70 becomes inoperative and valve 60 is shifted to the left by spring 61. Fluid from line 59 is directed through line 62 and throttle valve to the left end of cylinder 23 to rotate cam 22 in a clockwise direction. The actuating portions 28, 29 of cam 22 advances shoe 11 to engage workpiece 13 and feed it against the grinding wheel 44).

After the timing relay 66 operates, solenoid 46 is energized and valve 44 moves to the left to deliver pressure fluid to the left of cylinder 49 and retract slide 5%. When slide 5t} moves away from jet stop 53, the pressure in line 56 drops and pressure switch 64 is actuated to open contact 65 and reset timer 66.

Operation of the timing relay es opens switch 67 rendering solenoid 46 inoperative. Further operation depends upon movement to the right of the lever 45.

Contact 69 of switch 64 closes to energize solenoid in, shifting valve 69 t0 the right and directing fluid to the left end of cylinder 23 to reset shoe 11.

The arrangement above described provides for a sizer shoe which is held in retracted position except when positively advanced by the ring cam 22. The movement of the latter can be given gradual adjustment by control of the fiuid pressure in the cylinder 25. The extent of engagement between the cam land 29 and the button 18 controls the advance of the sizer shoe 11. The movement is terminated by engagement of the hardened face 51 with the abutment 35.

Reverse movement of the piston 26 permits the springs 8 and 9 to withdraw the sizer shoe 11 from engagement with the workpiece.

An adjustment once made of the button 18 controls the final position of the sizer shoe 11.

Adjustment of the screw 33 controls the duration of, and the amount of the fine grinding feed and the final position of the sizer shoe ll.

While the preferred form of the invention has been described and illustrated, it is to be understood that minor variations in arrangements, material and propertions are possible without departing from the scope of the invention as defined in the following claims.

What I claim is:

1. Feeding means for a sizer shoe comprising a pair of front and rear resilient retractile supports, a carriage mounted thereon, said carriage having a front work-engaging shoe and a rear abutment, acam rotatably mounted opposite said abutment, means to rotate the cam, said cam having a steep portion for engaging said abutment and advancing said carriage to bring the shoe rapidly into engagement with a workpiece and a second less steep portion for engaging said abutment to feed the workpiece against a grinding wheel 2. Feeding means for a sizer shoe comprising a pair of front and rear resilient retractile supports, a carriage mounted thereon, said carriage having a front workengaging shoe and a rear abutment, a cam rotatably mounted opposite said abutment, a motor for advancing the cam against the abutment in opposition to the supports and alternatively retracting the cam, a shoulder on said cam and an adjustable stop in the path of said shoulder limiting the advance of the carriage.

3. Feeding means for a sizer shoe comprising a pair of front and rear resilient retractile supports, a carriage mounted thereon, s-aid carriage having a front work-engaging shoe and a rear abutment, a cam rotatably mounted opposite said abutment, a raised land on said cam, an inclined slope adjacent said land, a motor for advancing the cam with the land against the abutment in opposition to the supports and alternatively retracting the said cam, a shoulder on the cam and an adjustable stop in the path of said shoulder limiting the advance of the carriage.

4. Feeding means for a sizer shoe comprising a pair of front and rear resilient retractile springs, a carriage mounted thereon, said carriage having a front work-engaging shoe and a rear abutment, a cam ring rotatably mounted opposite said abutment, a land on the ring,,a shoulder on the ring in spaced relation to the land, a motor for advancing the cam with the land against the abutment in opposition to the supports and alternatively retracting the said land, an adjustable fixed stop in the path of said shoulder limiting the advance of the carriage.

5. A machine for grinding a hollow cylindrical workpiece comprising means for rotatably supporting the workpiece on one of its end faces, peripherally spaced supports for the inner surface of the workpiece, a rotary grinding wheel, means for feeding the grinding wheel against the workpiece, means for stopping said feeding means, a sizer shoe mounted substantially opposite the point of contact between said grinding wheel and said workpiece, hydraulically operated means actuated by said stopping means for advancing said sizer shoe rapidly into engagement with said workpiece, and means for thereafter advancing said sizer shoe at a slower rate to feed said workpiece against said grinding wheel.

6. A machine for grinding the external surfiace of an annular workpiece to accurate size comprising means for supporting and rotating the workpiece operable on an end face of the workpiece, an arbor having peripherally spaced shoes engaging the internal surface of the workpiece, a rotary grinding wheel, means for feeding the grinding wheel against the workpiece, means for stopping the feed of the grinding wheel, means for feeding the workpiece agains tthe grinding wheel for finish grinding said workpiece to a predetermined diameter including a work-engaging shoe and hydraulically actuated means op enable upon stopping of said grinding wheel for moving said work engaging shoe rapidly into engagement with the workpiece and then slowly for finish grinding said workpiece to a predetermined diameter.

7. A machine for grinding hollow cylindrical workpieces comprising means for rotatably supporting a Workpiece on one of its end faces, peripherally spaced supports for the inner surface of the workpiece, a rotary grinding wheel, means for feeding said grinding Wheel against the workpiece, means for stopping said feeding means, a sizer shoe mounted substantially opposite the point of contact between said grinding wheel and said workpiece, means for advancing said sizer shoe rapidly into engagement with said workpiece, means for thereafter advancing said sizer shoe at a slower rate to feed said workpiece against said grinding wheel including a rotatable cam and hydraulic means for rotating said cam.

8. Feeding means for a sizer shoe comprising a pair of front and rear resilient retractile supports, a carriage mounted thereon, said carriage having a front work-engaging shoe and a rear abutment, hydraulically actuated means for advancing said carriage at a rapid rate to engage the shoe with a workpiece and then at a slower rate to feed said workpiece against a grinding wheel.

References Cited in the file of this patent UNITED STATES PATENTS 1,808,401 Cook et al. June 2, 1931 2,799,977 Jones et al. July 23, 1957 2,927,408 Cann Mar. 8, 1960 FOREIGN PATENTS 850,861 Germany Sept. 29, 1952 

